In 1981 Suda and his colleagues first reported the new activity of calcitriol namely its ability to differentiate the myeloid leukemia cells into normal monocytes-macrophages. However, the possibility of using calcitriol as an antileukemic drug was not feasible because of its potent calcemic effects. Based on these observations, several pharmaceutical companies initiated the synthesis of vitamin D analogs with the aim to separate the calcemic actions of calcitriol from its actions on regulating the cell growth and differentiation. As a result, numerous noncalcemic analogs with a potential for the treatment of leukemia and other cancers were synthesized. The group at Chugai introduced two characteristic analogs of opposite type namely, 22-oxacalcitriol (OCT) and 2beta-(3-hydroxypropoxy)calcitriol (ED-71) which have been shown to have therapeutic value and are already being used clinically. The work on OCT and ED-71 together with the work on calcipotriol and KH-1060 by Leo Laboratories, and 1alpha,25(OH)(2)-16-ene-23-yne-D(3) by Hoffmann-La Roche, vigorously stimulated research world-wide in the development of vitamin D analogs into pharmaceutical products. More recently new impressive vitamin D analogs such as 3-epi analogs, 19-nor analogs, 18-nor analogs, 2-methyl-20-epi-calcitriol, non-steroidal vitamin D analogs are being developed. The authors are convinced that various vitamin D analogs will become highly effective therapeutic agents at the clinical level in the new century, and also that a new theory on the mechanism of vitamin D action will be generated.

Animals↗

PubMedDate not supplied

Assessment of bone mass by image analysis of metacarpal bone roentgenograms: a quantitative digital image processing (DIP) method.

a digital processing (DIP) method for assessing bone mass was developed on the basis of image analysis of roentgenograms. Linearity between DIP values and the actual calcium carbonate content was scarcely affected even if roentgenograms were made with bone phantoms placed in different depths of water or by altering the voltage of X-ray generation. In clinical studies, coefficients of variation (CV) for various measurements were lower than 2.4%. When the correlations between the DIP values and the bone mineral densities in the distal one-third of the radius, and the 2nd to 4th lumbar vertebrae were investigated in 340 females, there were good positive correlations of r = 0.799, and r = 0.611, respectively (p less than 0.001). The DIP value was significantly lower in patients showing a low Singh index and in those with vertebral fractures than in other subjects. These results suggest that the DIP method provides an index with which to assess the efficacy of treatment and which can be used as a criterion in screening for osteoporosis.

Absorptiometry, Photon↗

PubMedDate not supplied

Indexes of bone mineral content on second metacarpal bone roentgenogram analyzed by digital image processing: a comparison with other bone mass quantifying methods.

A new photodensitometric technique (digital image processing, DIP) was performed to assess the bone mineral content of the metacarpal bone as a screening test for bone loss in 340 healthy or osteoporotic women as well as 35 steroid-dosed patients and 46 patients with chronic renal failure on hemodialysis. This procedure was compared with single photon absorptiometry and dual photon absorptiometry in terms of clinical value. Two bone mineral indexes, metacarpal index and sigma GS/D (the integrated bone mineral density of cortical and trabecular bone on a cross section in the middle of the second metacarpal bone), were equal to other methods in the quantification of decreases in bone mineral content due to aging in healthy or osteoporotic women. In addition, sigma GS/D was sensitive enough to detect decreases in bone mineral content in patients with vertebral fractures, on steroid therapy, and with chronic renal failure. Thus, sigma GS/D measured by DIP was shown to have clinical value as a tool in screening for decreased bone mineral content.

Absorptiometry, Photon↗